Associated objects may work too for simple cases. But another great solution I adopted successfully for a very large class was to rename ObjC HHFooBar into _HHFooBar and redefine HHFooBar as a Swift subclass of _HHFooBar. If possible I take the opportunity to drop the prefix too.

The Mac: Very happy to see double digit YOY growth in active install base of Macs, to new all-time high. Nearly 60% of purchases coming from customers who are new to Mac. YOY sales performance was impacted by MacBook Pro launch in early Q4 instead of June last year.

One thing, though: Q3 is traditionally when most of the US K-12 purchases happen, the institutional side of the education buying season (consumer purchases tend to happen in Q4). And iPad unit sales are up ever so slightly year-over-year, but Mac unit sales are off 13%.